LSTable: A New White-Box Cipher for Embedded Devices in IoT Against Side-Channel Attacks

Abstract

Embedded devices such as sensors and surveillance cameras play a critical role in the Internet of Things (IoT). However, their unattended and wireless features expose them to a high risk of side-channel attacks. These attacks exploit information leakage through side channels to deduce secret keys or even extract implementations of cryptographic algorithms. The possession of such knowledge empowers attackers to decrypt sensitive information transmitted among IoT devices, posing a significant threat to data confidentiality. To address this issue, we propose LSTable, a new white-box cipher enlightened by LS-Design. Instead of directly using secret keys for encryption and decryption, LSTable transforms secret keys into key-dependent lookup tables to mitigate side-channel attacks, and the size of these tables is designed to fit the hardware constraints of embedded devices. The security analysis of LSTable shows its security in both the black-box and white-box models. Furthermore, experimental evaluations on different devices exhibit that even the efficiency of the slowest instances of LSTable is 2.2 to 14.8 times that of existing space-hard white-box ciphers with IoT-friendly table sizes, while the energy consumption is only around 1/13 to 1/3.